Sleep disruption is one of the most common and potentially detrimental long-term side effects of chemotherapy in breast cancer patients. The majority of patients undergoing chemotherapy report acute sleep disturbances, and as many as 60% of survivors go on to develop chronic sleep disruption, which can persist for more than a decade following treatment. Despite this high incidence, the etiology of sleep disruption among breast cancer patients remains unknown. The goal of the proposed studies is to elucidate the physiological mechanisms through which chemotherapy contributes to the development of sleep disruption. Aim 1 will use mice to establish whether a causal relationship exists between chemotherapy-induced inflammation and sleep disruption. Specifically, we will determine whether regions of the brain associated with sleep have increased expression of proinflammatory cytokines after exposure to chemotherapy, and whether suppressing inflammation via minocycline, an anti-inflammatory drug already available for use in cancer patients, preserves sleep during and after treatment with chemotherapy. In Aim 2, we will characterize sleep quantity and quality in breast cancer patients prior to chemotherapy and during the survivorship period using self-report measures and objective actigraph, EEG and EMG measures collected during stays in the Ohio State University Sleep Disorders Clinic; these measures will be correlated with serum biomarkers of inflammation. This study will provide the most comprehensive analysis of sleep in breast cancer patients to date, and together with Aim 1 will determine whether an interventional sleep study using minocycline is warranted in breast cancer patients. The long-range goal of the proposed research is to improve the mental and physical health of cancer patients, as well as their quality of life, through the normalization of sleep during chemotherapy treatment and throughout the survivorship period.